Resist stripping method and apparatus

ABSTRACT

A method and an apparatus capable of stripping resist efficiently in a short amount of time. A stripping solution under high pressure is jetted from a nozzle to a rotating wafer. The resist layer on the wafer is applied with the jetted stripping solution, and the resist layer can be efficiently stripped in a short amount of time by the multiplied effect by the physical effect caused by the impact of the jetted stripping solution and the chemical effect of the stripping solution.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a resist stripping method andapparatus, and more particularly to a resist stripping method andapparatus which can remove the unnecessary resist from a substrate in aprocess of a lift-off method.

2. Description of Related Art

A lift-off method is one of the methods in a manufacturing process ofsemiconductor devices for planarizing a surface of an insulating layerthat covers wiring patterns and parts among the wiring patterns on asubstrate. In the lift-off method, the wiring patterns are formed on thesubstrate by etching, or the like, and then the insulating layer withthe same thickness as the thickness of the wiring patterns is depositedover the substrate by a method such as a chemical vapor depositionmethod without removing a resist, which was used as a mask in theetching. Thus, the insulating layer is deposited on the resist andnon-resist areas on the substrate, and the areas without the wiringpatterns are filled up with the insulating layer. Next, the resist andthe insulating layer that is deposited on the resist are stripped, andafter that, an insulating layer is further deposited over the substrate.As a result, the insulating layer with a planarized surface can beformed on the substrate on which the wiring patterns are formed.

As described above, the lift-off method requires a process to remove theresist and the insulating layer deposited on the resist. Conventionally,the process is performed by immersing the substrate in strippingsolution, which is a chemical solution for removing the resist from thesurface of the substrate. However, since the conventional method stripsthe resist only by a chemical effect of the stripping solution, thereare disadvantages in that the method is time consuming, and the resiststend to remain.

SUMMARY OF THE INVENTION

The present invention has been developed in view of the above-describedcircumstances, and has as its object the provision of a resist strippingmethod and apparatus that can efficiently strip a resist in a shortamount of time.

In order to achieve the above-described object, the present invention isdirected to a method for stripping resist from a substrate, comprisingthe step of: jetting stripping solution to the substrate.

According to the present invention, the resist on the substrate isapplied with the jetted stripping solution, and the resist can beefficiently stripped in a short amount of time by the multiplied effectby the physical effect caused by the impact of the jetted strippingsolution and the chemical effect of the stripping solution.

BRIEF DESCRIPTION OF THE DRAWINGS

The nature of this invention, as well as other objects and advantagesthereof, will be explained in the following with reference to theaccompanying drawings, in which like reference characters designate thesame or similar parts throughout the figures and wherein:

FIG. 1 is a view showing the entire structure of a resist strippingapparatus according to the first embodiment of the present invention;and

FIG. 2 is a view showing the entire structure of a resist strippingapparatus according to the second embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

This invention will be described in further detail by way of examplewith reference to the accompanying drawings.

FIG. 1 shows an entire structure of a resist stripping apparatusaccording to the first embodiment of the present invention.

As shown in FIG. 1, the resist stripping apparatus 10 comprises a waferholding device 12 for holding a substrate or a wafer W, and a jettingdevice 30 for jetting a chemical solution or a stripping solution and arinsing solution or pure water to the wafer W that is held by the waferholding device 12.

An explanation is given for a structure of the wafer holding device 12.A disc-shaped turntable 18 is arranged inside a sink 16, which isprovided on a stage 14. A suction chuck 20 is provided on the top of theturntable 18, and the wafer W is held on the suction chuck 20 bysuction. A spindle 22 is connected to the bottom of the turntable 18,and the lower end of the spindle 22 is connected with an output shaft ofa turntable driving motor 24. Driving the turntable driving motor 24rotates the turntable 18.

Next, an explanation is given for a structure of the jetting device 30.A pressure source of the jetting device 30 is a pump 32, which isoperated by an air motor 34. An air compressor 40 is connected to theinput side of the air motor 34 via a pipe 36 and a valve 38. Supplyingcompressed air from the air compressor 40 drives the air motor 34.

The input side of the pump 32 is connected with a stripping solutiontank 44 and a rinsing solution tank 46 via a pipe 42. A solution forstripping a resist (i.e. the stripping solution) is stored in thestripping solution tank 44, and a rinsing solution (e.g. pure water) isstored in the rinsing solution tank 46. A first valve 48 and a secondvalve 50 are arranged on the pipe 42. Operating opening and closing thefirst valve 48 and the second valve 50 switches the connection with thepump 32. Opening and closing of the first and the second valves 48 and50 are performed according to operation signals of a controller (notshown).

The output side of the pump 32 is connected with a gun 56 via anaccumulator 52 for stabilizing the jetting pressure and a pipe 54. Theend of the gun 56 is provided with a nozzle 58, and the strippingsolution or the rinsing solution under high pressure is jetted to thewafer W from the nozzle 58.

The gun 56 is supported with the end of an arm 62, which is connectedwith an output shaft of a motor 60. When the motor 60 is driven forturning the arm 62, the gun 56 is withdrawn from above the wafer W.

In the jetting device 30 with the above-described structure, when thepump 32 is operated by the air motor 34, the stripping solution in thestripping solution tank 44 or the rinsing solution in the rinsingsolution tank 46 is sucked into the pump 32 and supplied to the gun 56under high pressure. Then, the stripping solution or the rinsingsolution supplied to the gun 56 is jetted in a state of being atomized(reduced to fine particles).

Operation of the resist stripping apparatus 10 in the first embodimentas constructed above is as follows.

When the wafer W is placed on the suction chuck 20 by a transportingrobot (not shown), the wafer W is held on the suction chuck 20 bysuction. Then, the turntable driving motor 24 is driven and theturntable 18 rotates so as to rotate the wafer W, which is held on theturntable 18. At the same time, the motor 60 is driven to turn the arm62 so that the gun 56 is positioned above the wafer W.

Then, the air compressor 40 is operated and the compressed air issupplied to the air motor 34 so as to drive the air motor 34, and thepump 32 is operated by the air motor 34. At this time, the first valve48 is opened and the second valve 50 is closed. Thus, when the pump 32is operated, the stripping solution in the stripping solution tank 44 issucked into the pump 32. The stripping solution sucked into the pump 32is supplied to the gun 56 under high pressure, and is jetted to thewafer W from the nozzle 58 of the gun 56 in a state of being atomized.

A resist layer on the wafer W is applied with the jetted strippingsolution, and is stripped by the chemical effect of the strippingsolution. Moreover, the resist layer is cracked by impact caused bycollisions with the stripping solution jetted under high pressure; thusdissolution effect by the stripping solution is quickened. Further,because applying the stripping solution under high pressure rinses offthe stripped resist, the resist can be efficiently stripped.Furthermore, jetting the atomized stripping solution under high pressureeffectively applies the stripping solution to narrow gaps; therefore,the resist can be satisfactorily stripped without remaining.Used-stripping solution is drained via a drainpipe 26 from a drain hole16 a of the sink 16.

The stripping solution is jetted continuously for a predetermined time.The air compressor 40 is stopped after the predetermined time iselapsed. After that, the first valve 48 is closed and the second valve50 is opened.

Then, the air motor 34 is driven again to operate the pump 32, and therinsing solution in the rinsing tank 46 is sucked into the pump 32. Therinsing solution sucked into the pump 32 is supplied to the gun 56 underhigh pressure, and is jetted to the wafer W from the nozzle 58 of thegun 56 in a state of being atomized.

The wafer W is applied with the jetted rinsing solution, and thestripping solution that is adhered to the surface of the wafer W isrinsed off from the wafer W. The rinsing solution is jetted continuouslyfor a predetermined time. The air compressor 40 is stopped after thepredetermined time is elapsed. After that, the motor 60 is driven toturn the arm 62, so that the gun 56 is withdrawn from above the wafer W.

On the other hand, the turn table 18 is rotated continuously even afterthe jetting of the rinsing solution is stopped; thus the remainingrinsing solution on the wafer W is shaken off by the centrifugal forceby the rotation of the turn table 18; whereby the wafer W is dried. Thewafer W is dried continuously for a predetermined time. The turntabledriving motor 24 is stopped after the predetermined time is elapsed.Then the suction chuck 20 relieves the wafer W of the suction when therotation of the turn table 18 is stopped completely, and the wafer W onthe suction chuck 20 is transported to the next process by thetransporting robot (not shown).

As described above, according to the resist stripping apparatus 10 inthe first embodiment of the present invention, the resist can beefficiently stripped in a short amount of time by the multiplied effectby the physical effect caused by the impact of the stripping solutionjetted under high pressure and the chemical effect of the strippingsolution. Moreover, the multiplied effect inhibits burrs from generatingin boundaries between the wiring patterns and an insulating layer on thewafer W.

In addition, an explanation is given for the jetting pressure of thestripping solution or the rinsing solution jetted from the nozzle 58. Ifthe jetting pressure is less than 3 MPa, the physical effect caused bythe impact of the stripping solution is not sufficiently achieved, andif the jetting pressure is over 50 MPa, elements on the wafer W would bedamaged. Accordingly, the jetting pressure is preferably set in a rangebetween 3 MPa and 50 MPa.

In the first embodiment, the stripping solution or the rinsing solutionis jetted with the gun 56 being fixed at a certain position; however thestripping solution or the rinsing solution may be jetted while the gun56 is horizontally moving. In other words, the motor 60 is driven toswing the arm 62 in a predetermined angle range while the strippingsolution or the rinsing solution is being jetted, and then the strippingsolution or the rinsing solution may be jetted while the gun 56 isreciprocating. The moving mechanism is not limited to that; the movingmechanism may be constructed to horizontally slide the gun 56.

In the first embodiment, there is only one nozzle to jet the strippingsolution or the rinsing solution; however multiple nozzles may bearranged to jet the stripping solution or the rinsing solution fromplural locations. The multiple nozzles may be linearly or circularlyarranged.

In the first embodiment, the pump 32 is operated by the air motor 34;however a hydraulic motor, an electric plunger, or the like may be usedto operate the pump 32. Further, the rinsing solution may be chemicalsolution rather than pure water.

FIG. 2 shows the entire construction of a resist stripping apparatusaccording to the second embodiment of the present invention.

As shown in FIG. 2, the resist stripping apparatus 100 of the secondembodiment comprises a jetting type resist stripping apparatus 102, atransporting robot 104, a wafer collecting device 106, a cassettetransporting device 108, and an immersing type resist strippingapparatus 110.

The jetting type resist stripping apparatus 102 differs from the resiststripping apparatus 10 of the first embodiment in that the turn table 18is constructed to be able to move up and down. In other words, theturntable driving motor 24 for driving the turntable 18 is installed ona lifting table 112A of a lifting device 112. Operating the liftingdevice 112 moves the turntable 18 up and down. The other structures ofthe jetting type resist stripping apparatus 102 is the same as thestructures of the resist stripping apparatus 10 of the first embodiment;thus the members which are similar to those described with reference toFIG. 1 are denoted by the same reference numerals, and they will not beexplained.

The transporting robot 104 receives the wafer W on the suction chuck 20of the turn table 18, which is lifted up to a predetermined receivingposition, and the transporting robot 104 stores the wafer W into acassette 114 of the wafer collecting device 106. The transporting robot104 has multi-joints. The end of a first arm 104A, which is able toturn, has a second arm 104B, which is also able to turn, and the end ofthe second arm 104B has a hand 104C, which is able to turn as well. Thewafer W is held by a suction pad 104D, which is provided at the end ofthe hand 104C, and transported horizontally.

The wafer collecting device 106 has a cassette lifting device 118 on astage 116. The cassette 114 is positioned and placed on a lifting table118A of the cassette lifting device 118, and the wafers W are stored oneby one separately in the cassette 114. The cassette lifting device 118lifts the cassette 114 one level each time one wafer W is stored in thecassette 114; thus the wafers W that are horizontally transported by thetransporting robot 104 are stored one by one in the cassette 114.

The cassette transporting device 108 comprises a belt conveyer. Thetransporting device 108 transports the cassette 114 from the liftingtable 118A of the wafer collecting device 106 to a lifting table 126A ofthe immersing type resist stripping apparatus 110.

The immersing type resist stripping apparatus 110 immerses the wafers Win the stripping solution 124 in order to strip the resist on the waferW. The immersing type resist stripping apparatus 110 has a strippingvessel 122 installed on a stage 120, and the stripping solution 124 isstored in the stripping vessel 122. The stripping vessel 122 has thelifting table 126A on which the cassette 114 is placed, and the liftingtable 126A is operated by a lifting device 126 and moved up and down inthe stripping vessel 122.

The operation of the resist stripping apparatus 100 in the secondembodiment as constructed above is as explained below.

First, the wafer W is placed on the suction chuck 20 of the jetting typeresist stripping apparatus 102 by the transporting robot (not shown),and the wafer W is held on the suction chuck 20 by suction. Next, theturntable driving motor 24 is driven and the turntable 18 rotates so asto rotate the wafer W, which is held on the turntable 18. At the sametime, the motor 60 is driven to turn the arm 62, and the gun 56 ispositioned above the wafer W.

Then, the pump 32 is operated (see FIG. 1) and the stripping solutionunder high pressure is jetted from the nozzle 58 of the gun 56 to thewafer W in the state of being atomized. The resist layer on the wafer Wis applied with the jetted stripping solution, and is stripped by thechemical effect of the stripping solution. Moreover, the resist layer iscracked with the impact caused by the collisions of the strippingsolution jetted under high pressure. Thus, the dissolution effect by thestripping solution is quickened.

The stripping solution is jetted continuously for a predetermined time,and after the predetermined time is elapsed, the pump 32 is stopped.Then, the motor 60 is driven to turn the arm 62, and the gun 56 iswithdrawn from above the wafer W. At the same time, the turntabledriving motor 24 is stopped, and the turntable 18 is stopped.

Then, the lifting device is operated to lift up the turntable 18 to thepredetermined receiving position, and the suction chuck 20 relieves thewafer W of suction. After that, the wafer W is received from the suctionchuck 20 by the transporting robot 104, and the wafer W is stored in thecassette 114 of the wafer collecting device 106.

By the above-described sequential process, the jetting type resiststripping from the first wafer W is completed. The same sequentialprocesses are performed to strip the resist of the second and thirdwafers, and so on. When all the wafers W are stored in the cassette 114,the jetting type resist stripping is completed.

Next, the cassette transporting device 108 is operated to transport thecassette 114 that is placed on the lifting table 118A to the liftingtable 126A of the immersing type resist stripping apparatus 110. At thistime, the lifting table 126A is positioned at a predetermined receivingposition.

The lifting table 126A on which the cassette 114 is placed is moved downby the lifting device 126; thereby the cassette 114 is immersed in thestripping solution 124, which is stored in the stripping vessel 122. Theresist on the wafers W in the cassette 114 that is immersed in thestripping solution 124 is stripped by the chemical effect of thestripping solution 124.

The wafers W are immersed in the stripping solution 124 for apredetermined time. Since the jetting type resist stripping from thewafers W have already been performed, thus the immersing can becompleted in a short amount of time. Moreover, the resist layers havebeen cracked by the jetting type resist stripping, thus the corrosioneffect by the stripping solution is quickened, and the resist can beeasily stripped.

When the predetermined time is elapsed since the cassette 114 isimmersed in the stripping solution 124, the lifting device 126 isoperated and the lifting table 126A is moved up so as to lift up thecassette 114 from the stripping solution 124. Then the lifted-upcassette 114 is transported to the next process by a transporting means(not shown).

As described above, the resist stripping apparatus 100 of the secondembodiment can strip the resist more reliably by jointly using thejetting type resist stripping and the immersing type resist stripping.In other words, because the resist layer is cracked by the jetting typeresist stripping beforehand, the dissolution effect of the strippingsolution is quickened at the immersing type resist stripping;consequently the resist can be efficiently stripped in a short amount oftime.

In the second embodiment, the jetting type resist stripping is performedby jetting the stripping solution; however liquid (e.g., pure water)which is not the stripping solution may be jetted. In this case, theresist can not be stripped with the chemical effect of the strippingsolution, but the resist can be cracked by colliding with the jettedliquid under high pressure. Thus, the resist can be efficiently strippedin a short amount of time at the immersing type resist stripping.

In the second embodiment, the immersing type resist stripping isperformed after the jetted type resist stripping is performed, but theymay be performed in the reverse order. That is, the resist may bestripped by immersing the wafer W in the stripping solution at first fora predetermined time and then applying the stripping solution under highpressure to the wafer W for a predetermined time. In this case, theresist in narrow gaps that could not be removed by the immersing typeresist stripping can be satisfactorily removed by the jetting typeresist stripping. In this case, if the stripping solution is jetted andthen the rinsing solution under high pressure is jetted for thepredetermined time and after that the spinning drying is performed asdescribed in the first embodiment, the resist stripping, rinsing, anddrying of the wafer W can be sequentially performed, so that the processefficiency of the wafer W is improved.

Further, according to the following procedure, the resist can be moreefficiently stripped.

First, the liquid, which may be the stripping solution, or it may not,under high pressure (approximately 15 MPa) is jetted to the wafer W fora predetermined time in order to crack the resist layer. Next, the waferW is immersed in the stripping solution for a predetermined time. Thenthe stripping solution under high pressure (approximately 5 MPa) isjetted to the wafer W. By this procedure, the resist can be efficientlyremoved. Same as the procedure described above, this case also canimprove the process efficiency of the wafer W if the jetting type resiststripping using the stripping solution is performed and then the rinsingsolution under high pressure is jetted for the predetermined time andnext the spinning drying is performed, the resist stripping, rinsing anddrying of the wafer can be sequentially performed, so that the processefficiency of the wafer W is improved.

Additionally, because of the same reason as the first embodiment, therange of the jetting pressure of each solution from the nozzle 58 ispreferably set to be 3 MPa-50 MPa.

As described above, according to the resist stripping method andapparatus of the present invention, the resist on the substrate isstripped by the physical effect caused by the impact of the jettedstripping solution, and the chemical effect of the stripping solution.Therefore, the resist on the substrate can be efficiently removed in ashort amount of time by the multiplied effect by the chemical andphysical effects.

It should be understood, however, that there is no intention to limitthe invention to the specific forms disclosed, but on the contrary, theinvention is to cover all modifications, alternate constructions andequivalents falling within the spirit and scope of the invention asexpressed in the appended claims.

What is claimed is:
 1. An apparatus for stripping resist from asubstrate, comprising: a table for supporting the substrate; and ajetting device for jetting stripping solution to the substrate on thetable at sufficiently high fluid pressure to achieve a collectiveremoval effect of physically cracking the resist due to the impact ofthe jetted fluid without damaging the substrate combined with a chemicalremoval by the stripping solution of the resist from the substrate. 2.The apparatus of claim 1, wherein the jetting apparatus jets thestripping solution under pressure substantially 3 MPa to substantially50 MPa, whereby the jetted stripping solution is reduced to fineparticles.
 3. The apparatus of claim 1, further comprising: a vessel forstoring the stripping solution; and an immersing device for immersingthe substrate into the stripping solution in the vessel.
 4. Theapparatus of claim 1, further comprising: a jetting device for jettingrinsing solution to the substrate.
 5. The apparatus of claim 1, whereinthe jetting apparatus jets the stripping solution under a pressure ofbetween 3 MPa and 50 MPa, whereby the jetted stripping solution isreduced to fine particles.